1. Field of the Invention
The present invention relates to data communications, and, more particularly, to a method and apparatus for tunneling packets between network elements.
2. Description of the Related Art
In the market for metropolitan area networks, customers often utilize a service provider's virtual local area network (VLAN) to achieve transparent connectivity for an Ethernet LAN across the service provider's network. However, it has become apparent that various protocols that a customer might employ (e.g., for management of the customer's network) produce undesirable results when operated in a LAN environment in which at least a portion of the LAN is coupled to the rest of the LAN through the use of a service provider VLAN as transport vehicle.
Additionally, service providers of Ethernet LAN services, such as proprietors of transparent LAN services (TLS) networks, desire the ability to have multi-path redundancy when using 802.1Q tunneling. Moreover, such service providers desire to make the service provider network “cloud” transparent to PDUs (Protocol Data Units) such as those generated by discovery protocols (DPs, such as Cisco Systems' Cisco Discovery Protocol (CDP)) and the like, in order to improve the flexibility and manageability of the network. Current implementations of 802.1Q tunneling (certain implementations of which are referred to as QinQ, 1Q-in-1Q or tag stacking, among others) do not allow a customer switch to be dual-homed to two different service provider switches. However, such implementations do allow link redundancy between a single-homed customer switch and a service provider switch. Currently, there is also no support for tunneling PDUs of other protocols, such as discovery protocols (e.g., Cisco Discovery Protocol (CDP)) or VLAN trunking protocol (VTP), for example.
What is therefore desired is an approach that permits the tunneling of PDUs, preferably from a variety of protocols. Moreover, by using the capability of tunneling such PDUs, TLS networks could be built with redundant links to the same or different service providers. It is also desirable to allow a customer to discover its switches on the other end of the tunnel as if those switches were physically adjacent. Enterprise customers may also desire to tunnel PDUs in order to unify their sites' VLAN management across a TLS network, among other such functionality.